JPH051796A - Electric fusion-bonded joint and its molding method - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Regarding the electric fusion joint and its forming method, the joint heating element wire does not extend to the cold zone, and the entire inner surface can be formed by uncolored synthetic resin and its forming. Provide a way. The end portion and at least the cold zone of the inside of the joint pipe are defined by spacers integrated with the inner surface of the pipe. Further, in order to mold such a joint, a ring-shaped or sleeve-shaped spacer 2 is provided at a portion of the divided molding core 10 which is in contact with the collar of the body and an appropriate portion of the body.
0 and 20a are fitted together, the cores are engaged with each other, the coated heating element wire A is wound around the core body other than the spacer, and the wire is made continuous by the notch provided on the outer periphery of the spacer. The core is set in the mold 30 and the molten thermoplastic synthetic resin is injected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fusion joint and a molding method thereof, which are used for pipe construction and the like made of a thermoplastic polymer material.

[0002]

2. Description of the Related Art When connecting a pipe P made of a thermoplastic polymer material such as polyolefin or polyamide, as shown in FIG. 13, a joint C in which a coated heating element wire A is coiled around an inner surface thereof. Is used.

That is, heat is generated by passing an electric current through the heating element wire A, and the inner surface of the joint C and the outer surface of the tubing P are fused.

In such an electric fusion joint, the heating element wire A is not wound to the end portion, but the space S is left. This is to prevent accidents such as the filament A bulging outward from the end portion during heat fusion, exposing the heating element, and igniting the synthetic resin.

Similarly, a space S is formed inside. This is also to prevent an accident in which the heating element is exposed further inside from the tip of the tubing P during fusion bonding.

Such a space S is called a cold zone. To provide the cold zone at the time of molding the pipe joint, the heating element wire A is wound around the molding core K as shown in FIG. At this time, it is necessary to finish winding before this, without winding until it comes into close contact with the color L. The same applies to the inside. That is, the space S similar to the above must be provided at the time of winding.

Such work not only requires a great deal of skill, but it is also necessary to lock the middle part of the heating element wire that has been wound on the core K by some method, so that the workability is extremely poor. Moreover, there is a large variation in quality.

[0008] Further, for example, synthetic resin pipes for supplying drinking water are required to have at least the inner surface containing no coloring agent or filler.

However, in the case of using the pipe joint C as shown in FIG. 13, even if a colorant is mixed in the pipe portion, it is assumed that the coated heating element wire A completely covers the inner surface of the pipe body. The above requirements can be met if the coating of the strand A that is wound and formed of non-colored and additive-free synthetic resin is formed.

However, since there is the space S, that is, the cold zone and the exposed portion D inside thereof, the entire pipe joint C must be formed of the required synthetic resin, and an increase in cost cannot be avoided.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to make it possible to form only the inner surface of a pipe joint with a required material and, at the same time, to form a cold zone extremely easily.

[0012]

In order to solve the above-mentioned problems, a first invention is an electric fusion joint in which a coil of a coated heating element wire is integrally formed on the inner surface of the joint tube, and At least the cold zones at the ends and inside are partitioned by the spacer integrated with the inner surface of the joint pipe body.

Further, in order to mold the electric fusion-bonded joint, a ring-shaped or sleeve-shaped spacer is fitted to a portion of the divided molding core which is in contact with the collar of the body and other appropriate portions, and the cores are engaged with each other. After fitting, the coated heating element wire is wound around the core body other than the spacer, the wire is continuous by the notch provided on the outer periphery of the spacer, and the core is set in a mold to melt the molten resin. Was to be injected.

[0014]

Since the cold zone is divided by the spacer, the heating element wire never extends to the cold zone.

Further, if the spacer is formed of uncolored synthetic resin together with the coating of the heating element wires, the entire inner surface of the joint is composed of uncolored synthetic resin, so that it can be used as a supply line for drinking water or the like. .

In the molding method, it is sufficient to wind the heating element wire around the body of the molding core except for the spacer portion, and no skill is required. Further, since a notch is provided on the outer periphery of the spacer, it is possible to introduce the wound heating element wire into the adjacent core body portion or to draw out the wound heating element wire to the outside. You can

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, a method of forming an electric fusion joint will be described with reference to FIGS. 1 to 9.

FIG. 1 shows a molding core used in this molding method. As shown in the figure, the core 10 can be divided into two, and includes sub-cores 11 and 11a.

One of the sub-cores 11 has a large-diameter collar 1
2 and a body 13 extending from the body 2 are provided.
A locking hole 14 is formed inward from the end surface of the hole 3, and a positioning hole 15 is provided at the bottom of the hole 14. Also,
The collar 12 is provided with a through groove 16 for the coated heating element wire.

The other sub-core 11a is also provided with a similar collar 12a and a body portion 13a. A locking rod 14a adapted to the locking hole 14 extends from the tip of the body portion 13a. A positioning pin 15a corresponding to the positioning hole 15 is provided at the tip of the rod 14a. Further, the collar 12a is provided with a through groove 16a for the coated heating element wire.

Next, the spacer fitted to the molding core 10 will be described.

As shown in FIGS. 2 and 3, the spacer 20
Has a ring shape and is preferably made of uncolored synthetic resin. A notch 21 is provided on the outer periphery of the spacer 20. The notch 21 is for passing the coated heating element wire as described later.

Although the outer peripheral surface 22 of the spacer 20 is a tapered surface as is apparent from FIG. 3, the outer peripheral surface 22a may be flat as shown in FIG.
Further, the stopper 23a may be formed. These spacers 20 and 20a are used depending on the application. The shape of the spacer is not limited to the above, and may be appropriately selected according to the application place.

The spacers 20 and 20a as described above are fitted to the molding core 10 as shown in FIG.

First, the spacer 20 is fitted to the body portion 13 so as to come into contact with the collar 12 of the sub core 11, and the spacer 20 is fitted to the body portion 13a so as to come into contact with the collar 12a of the sub core 11a. Further, the spacer 20a is fitted to the locking rod 14a so that the stopper 23a contacts the end surface of the body portion 13a and a part of the spacer 20a covers the end portion of the body portion 13a.

Then, the locking rod 14a is inserted into the locking hole 14, the pin 15a and the hole 15 are aligned with each other, and the pin 15a
Is inserted into the hole 15, the assembling of the molding core 10 is completed.

As shown in FIG. 7, the coated heating element wire A is wound around the molded core 10 which has been assembled.

First, the wire A is passed through the groove 16 of the collar 12 through the notch 21 of the spacer 20, and the core body 13 is sequentially spirally wound from the portion in contact with the spacer 20. When the winding reaches the tip of the body 13 and contacts the spacer 20a,
The other body 13 through the notch 21a of the spacer 20a
Starting to wind from the tip of a and reaching the spacer 20, the strand A is pulled out from the notch 21 through the groove 16a.

As shown in FIG. 8, the molding core 10 around which the wire A is wound is inserted into the molding die 30, and the molten thermoplastic synthetic resin is injected into the die 30.

After cooling and hardening, the mold 30 and the core 10 are disassembled and the molded product is taken out.

FIG. 9 shows the obtained electric fusion joint 40. As shown in the figure, the three spacers 20, 20a, 20 and the coil of the coated heating element wire A are integrally formed on the inner surface of the tubular body 41, and each spacer defines a space S to be a cold zone. There is.

The space S is effective as a cold zone even when the end surface of the pipe P is accidentally cut obliquely as shown by the chain line in FIG.

The coated heating element wire A is a heating element such as a nichrome wire or a carbon wire provided with a single-layer or multi-layer coating layer, and at least the outermost layer is made of thermoplastic synthetic material. The structure does not matter as long as it is made of resin.

When the electric fusion joint 40 is an elbow, the body portions 13 and 13a of the sub cores 11 and 11a may be bent as shown in FIG. Others are the same as that of FIG.

In the state shown in FIG. 10, the spacers 20 and 20 are fitted so as to contact the collars 12 and 12a, respectively.
Curved sleeve spacers 20b as shown in FIG. 1 are fitted to the tip ends of the body portions 13 and 13a, respectively, to assemble the molding core 10.

Then, the three spacers 20, 20b, 2
In the same manner as described above, the coated heating element wire A is wound around the body portions 13 and 13a other than 0, and the coated heating element wire A is inserted into the mold and the melted thermoplastic synthetic resin is injected, followed by cooling and hardening.

The obtained elbow-type electric fusion joint 40 is shown in FIG. As shown in the figure, three spacers 20, 20b, 20 and a coil of the coated heating element wire A are integrally formed on the inner surface of the tubular body 41, and each spacer defines a cold zone.

In addition to the above, the electric fusion joint can be molded in the same manner as described above regardless of the shape, such as cheese type or cross type.

[0040]

As described above, according to the present invention, since the cold zone of the electric fusion joint is limited by the spacer as described above, the heating element wire does not extend to the cold zone, and the ignition occurs during electric fusion. If the spacer is made of uncolored synthetic resin together with the coating of the heating element wires, the entire inner surface of the joint will be made of uncolored synthetic resin, and the joint tube will be colored. However, it can be used for a pipeline for supplying drinking water or the like, and the laying cost can be reduced.

Further, in the molding method, the cold zone is naturally formed only by wrapping the portion other than the spacer portion in the step of winding the heating element wire around the body portion of the molding core, so that no skill is required. , Workability is improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a molding core.

FIG. 2 is a front view showing a spacer.

FIG. 3 is a vertical sectional view of the same.

FIG. 4 is a front view showing another example of the spacer.

FIG. 5 is a vertical sectional view of the same.

FIG. 6 is a front view showing a state in which a spacer is fitted to the molding core.

FIG. 7 is a front view showing a state in which a molded core is assembled and a coated heating element wire is wound.

FIG. 8 is a perspective view showing a state where the above molding core is set in a mold.

FIG. 9 is a longitudinal sectional view showing an example of an electric fusion joint.

FIG. 10 is a front view showing another example of the molding core.

FIG. 11 is a front view showing a state in which the same is assembled.

FIG. 12 is a vertical sectional view showing an elbow-type electric fusion-bonded joint.

FIG. 13 is a vertical sectional view showing a conventional electric fusion joint.

FIG. 14 is a front view showing a conventional molding core.

[Explanation of symbols]

A coated heating element wire C joint P tubing S space K molding core L color D exposed part 10 Molded core 11, 11a Sub core 12, 12a color 13, 13a body 16, 16a groove 20, 20a, 20b spacer 21, 21a Notch 30 molds 40 Electric fusion joint 41 tube

Claims (3)

[Claims] 1. A joint in which a coil of a coated heating element wire is integrally formed on the inner surface of a joint pipe body, and at least a cold zone at the end and inside of the joint pipe body is integrated on the inner surface of the joint pipe body. An electric fusion-bonded joint characterized in that it is partitioned by a spacer that is formed. 2. The electric fusion joint according to claim 1, wherein the spacer is made of uncolored synthetic resin. 3. A ring-shaped or sleeve-shaped spacer is fitted to a portion of the divided molding core that comes into contact with the collar of the body portion and an appropriate portion of the body portion, and after the cores are engaged with each other, cores other than the spacers are fitted. It consists of winding a coated heating element wire around the body, continuing the wire through a notch provided on the outer periphery of the spacer, setting this core in a mold, and injecting molten thermoplastic synthetic resin. A method for forming an electric fusion joint.